1. Field of the Invention
The present invention relates to a Schmitt trigger circuit, and more particularly, to a Schmitt trigger circuit having hysteresis characteristics, in which a release point and an operating point are determined based on a width of an inputted pulse.
2. Description of the Related Art
The field of sensors is closely connected to other industrial fields, and is currently utilized in various other fields having both industrial and consumer applications. Typically, various types of sensors such as a piezoelectric sensor, a magnetic sensor, and the like may be used, and most of the sensors may be implemented such that physical phenomena are able to be detected, and the detected physical phenomena may be converted to corresponding electrical signals to be outputted. For example, the piezoelectric sensor may detect physical momentum and output the detected physical momentum as an electrical signal, and the magnetic sensor may detect change in a magnetic field to output the detected change as an electric signal.
The above described sensors converting physical phenomena to the electrical signal may be mainly implemented in an analog type; however, a method has recently been developed in which digital elements may be partially mixed therein. Analog type sensors have advantages, in that an area for implementing the sensor is small and a sensor response speed is fast; however, analog type sensors also have disadvantages in that the power consumption thereof is large and the sensitivity thereof may be deteriorated.
More specifically, the conventional analog type sensor may amplify minute output signals obtained from a sensor element using an amplifier, and output an amplified analog waveform using a Schmitt trigger circuit. Since differential signals outputted from the sensor element typically use a differential amplifier, a circuit for removing an offset of the amplifier may be needed, thereby causing additional costs.
In addition, since the signals outputted from the sensor element may have noise contained therein, the Schmitt trigger circuit having hysteresis characteristics may be needed for the purpose of output stabilization. In the Schmitt trigger circuit used in the conventional analog type sensor, it may be significantly difficult to accurately set and match a release point and an operating point. Due to this problem, sensitivity may be deteriorated, and thereby changes between the release point and the operating point may be increased. Also, when sweeping of a gap between the release point and the operating point occurs, power consumption may be rapidly increased.